Opionion of Holme Roberts & Owen re: Tax Matters

We have acted as special counsel for Mallon Resources Corporation (“MRC”), a Colorado corporation, with respect to certain United States federal income tax matters in connection with (i) the Merger, as defined and described in the Agreement and Plan of Merger dated as of October 1, 2002 (the “Merger Agreement”) by and among Black Hills Corporation (“BH”), Black Hills Acquisition Corp. (“Merger Sub”) and MRC and (ii) the preparation of the discussion set forth under the caption “Certain Material United States Federal Income Tax Consequences” (to the extent that discussion relates to the shareholders of MRC) in the proxy statement/prospectus (the “Prospectus”) included as part of the Registration Statement on Form S-4, filed with the Securities and Exchange Commission (the “Commission”) on November 27th, 2002 in connection with the Merger.

This opinion is rendered in connection with the discussion set forth under the caption “Certain Material United States Federal Income Tax Consequences” in the Prospectus, to the extent that such discussion relates to the shareholders of MRC. In rendering this opinion, we have examined the Merger Agreement, the Prospectus and such other documents as we have deemed necessary or appropriate in order to enable us to render our opinion. For purposes of this opinion, we have (with your permission and without any investigation or independent verification) assumed (i) that the documents that we have examined constitute legal, valid and binding obligations of the parties thereto, enforceable against such parties in accordance with their terms, (ii) that the Merger will be consummated in the manner described in Merger Agreement and the Prospectus, (iii) that the Merger will be a valid merger under applicable state law, and

As to all factual matters material to the opinions expressed herein, we have (with your permission and without any investigation or independent verification) relied upon, and assumed the accuracy and completeness of, the representations, warranties and covenants contained in the Merger Agreement and the Prospectus and those made by BH (together with Merger Sub) and MRC in letters delivered to us dated as of November 26th, 2002 and November 25th, 2002, respectively. We have also assumed that the parties to the Merger Agreement, Prospectus and such letters will act in accordance with, and will refrain from taking any action that is forbidden by, the terms and conditions thereof.

Our opinion is based on the Internal Revenue Code of 1986, as amended (the “Code”), applicable Treasury regulations, and publicly available administrative interpretations and court decisions in effect as of the date of the Prospectus. The Code and Treasury regulations and the interpretation thereof by the Internal Revenue Service (the “IRS”) and the courts are subject to change, and any changes could be applied retroactively.

Subject to the assumptions, conditions and qualifications described herein and under the caption “Certain Material United States Federal Income Tax Consequences” in the Prospectus, we are of the opinion that the discussion under the caption “Certain Material United States Federal Income Tax Consequences” in the Prospectus describes the United States federal income tax consequences of the Merger that are likely to be material to the shareholders of MRC.

Our opinion represents our current legal judgment on the specific issues addressed based on the assumptions, conditions, qualifications and applicable law described above and it has no official legal status of any kind. The IRS may take a position contrary to our opinion and, if the matter is litigated, a court could reach a contrary decision. The opinions expressed herein are rendered as of the date hereof. We do not undertake to advise you of matters that may come to our attention subsequent to the date hereof and that may affect the opinions expressed herein, including without limitation, future changes in applicable law. This letter is our opinion as to certain legal conclusions as specifically set forth herein and is not and should not be deemed to be a representation or opinion as to any factual matters. The opinions expressed herein may be relied upon only by the addressee hereof in connection with the transactions provided for by the Merger. The

opinions expressed herein may not be quoted in whole or in part or otherwise used or referred to in connection with any other transactions and may not be furnished to or filed with any governmental agency or other person or entity without the prior written consent of this firm.

In accordance with the requirements of Item 601(b)(23) of Regulation S-K under the Securities Act of 1933, as amended (the “Securities Act”), we hereby consent to the filing of this opinion as an exhibit to the Prospectus and to the reference to our firm under the captions “Certain Material United States Federal Income Tax Consequences” and “Legal Matters” in the Prospectus. In giving such consent, we do not thereby admit that we are in the category of persons whose consent is required under Section 7 of the Securities Act or the rules and regulations of the Commission thereunder.